Submitted to: Poultry Science Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: March 13, 1995
Publication Date: N/A
Technical Abstract: Aspergillosis is an economically significant disease of commercially raised turkeys. Turkey aspergillosis is caused by Aspergillus fumigatus and less commonly by other Aspergillus species. Avian aspergillosis is most often associated with infection of the pulmonary system. Little is known about the way the disease develops in turkeys, especially at the very early stages of infection. We have conducted experiments to establish an intra- airsac model for consistent challenge, to determine the role of immuno- suppression in lowering resistance, and to evaluate the efficacy of vaccination. The severity of aspergillosis produced by airsac inoculation with A. fumigatus is dose-dependent. Turkeys treated with the immuno- suppressive agent dexamethasone prior to inoculation have a lowered resistance to aspergillosis. There is also a shift in the relative proportion of white blood cell types in circulation; there is a relative increase in heterophils and decrease in lymphocytes. We have found that vaccination may limit mortality, but exacerbates the airsac lesions that result in condemnation of carcasses at slaughter. In addition, we have developed a system to study the fine detail of healthy and diseased airsacs by microscopy. These are new and important accomplishments that emphasize the complexity of the disease and provide tools to study the initial host parasite interaction that culminates in aspergillosis.